Semiconductor integrated circuits may be subject to malfunction or inoperability during operation caused by physical damage, for example cracks, of the integrated circuit (IC) die due to for example physical stress or heat. Especially when being used in a safety critical system such as for example a car safety system, this may result in a dangerous situation for a user of the system. Therefore, physical damage of the die must be handled properly.
A measurement for performance of a safety function or a target level of risk reduction is given by the Safety Integrity Level (SIL) which is defined for example by the International Electrotechnical Commission's (IEC) standard IEC 61508 as a relative level of risk-reduction provided by a safety function.
Further, steps of semiconductor integrated circuit fabrication such as the step of wafer dicing may involve applying physical stress to the die which may result in physical damage especially of border areas, i.e. wafer dicing may damage the die areas close to their edges. Later on, the die may get damaged for example during assembly in a system, for example when being placed on a printed circuit board.
In U.S. Pat. No. 5,723,875, a chip damage detection circuit for semiconductor IC is shown wherein the chip contains a chip check circuit for applying a scan testing technique. An actively driven detector line extends through several observed circuits. A signal is applied to the line and a possible damage is derived from monitoring variation of the output signal over time.
In US 2008/0184083 A1, another dynamic circuit and method for physical defect detection of an integrated circuit is shown. Here, a test line on the integrated circuit chip is connected to a power supply and to a complex continuity sense circuit for deriving damage from observed continuous current through the test line and detection of differences.
In KR10-2007-0089500, a circuit for detecting a defect of a repair fuse in a semiconductor device is shown. A first sense circuit is wired to an address fuse for sensing current flow through the fuse by observing a potential change at the fuse, a second sense circuit is wired to a repair fuse. Comparison of both sensed signals is used for determining operability of the fuses.
In JP09-129830, a semiconductor integrated circuit having damage detection means is shown. Here, a well potential monitoring circuit is integrated with the circuit to be observed. The monitoring circuit outputs an anomaly detection signal when a potential of a portion of a well in the substrate located within the observed integrated circuit is detected to be out of a predetermined range.